Bow And Arrow.

If you stand on a beach and notice the tide moving far, far away from the shoreline...and receeding to an unusually low level, think Bow And Arrow.

The Japanese word 'Tsunami' consists of two words:
Tsu = Harbor; Nami = Wave.

The waves roll far away from the shoreline making the entire shoreline look like a desert...then, come racing back at 500 miles per hour.

The momentum of tidal waves, are that of a Bow And Arrow.